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diff --git a/docs/running-on-yarn.md b/docs/running-on-yarn.md index 3bd16bf60c..f2fbe3ca56 100644 --- a/docs/running-on-yarn.md +++ b/docs/running-on-yarn.md @@ -476,3 +476,99 @@ If you need a reference to the proper location to put log files in the YARN so t - In `cluster` mode, the local directories used by the Spark executors and the Spark driver will be the local directories configured for YARN (Hadoop YARN config `yarn.nodemanager.local-dirs`). If the user specifies `spark.local.dir`, it will be ignored. In `client` mode, the Spark executors will use the local directories configured for YARN while the Spark driver will use those defined in `spark.local.dir`. This is because the Spark driver does not run on the YARN cluster in `client` mode, only the Spark executors do. - The `--files` and `--archives` options support specifying file names with the # similar to Hadoop. For example you can specify: `--files localtest.txt#appSees.txt` and this will upload the file you have locally named `localtest.txt` into HDFS but this will be linked to by the name `appSees.txt`, and your application should use the name as `appSees.txt` to reference it when running on YARN. - The `--jars` option allows the `SparkContext.addJar` function to work if you are using it with local files and running in `cluster` mode. It does not need to be used if you are using it with HDFS, HTTP, HTTPS, or FTP files. + +# Running in a Secure Cluster + +As covered in [security](security.html), Kerberos is used in a secure Hadoop cluster to +authenticate principals associated with services and clients. This allows clients to +make requests of these authenticated services; the services to grant rights +to the authenticated principals. + +Hadoop services issue *hadoop tokens* to grant access to the services and data. +Clients must first acquire tokens for the services they will access and pass them along with their +application as it is launched in the YARN cluster. + +For a Spark application to interact with HDFS, HBase and Hive, it must acquire the relevant tokens +using the Kerberos credentials of the user launching the application +—that is, the principal whose identity will become that of the launched Spark application. + +This is normally done at launch time: in a secure cluster Spark will automatically obtain a +token for the cluster's HDFS filesystem, and potentially for HBase and Hive. + +An HBase token will be obtained if HBase is in on classpath, the HBase configuration declares +the application is secure (i.e. `hbase-site.xml` sets `hbase.security.authentication` to `kerberos`), +and `spark.yarn.security.tokens.hbase.enabled` is not set to `false`. + +Similarly, a Hive token will be obtained if Hive is on the classpath, its configuration +includes a URI of the metadata store in `"hive.metastore.uris`, and +`spark.yarn.security.tokens.hive.enabled` is not set to `false`. + +If an application needs to interact with other secure HDFS clusters, then +the tokens needed to access these clusters must be explicitly requested at +launch time. This is done by listing them in the `spark.yarn.access.namenodes` property. + +``` +spark.yarn.access.namenodes hdfs://ireland.example.org:8020/,hdfs://frankfurt.example.org:8020/ +``` + +## Launching your application with Apache Oozie + +Apache Oozie can launch Spark applications as part of a workflow. +In a secure cluster, the launched application will need the relevant tokens to access the cluster's +services. If Spark is launched with a keytab, this is automatic. +However, if Spark is to be launched without a keytab, the responsibility for setting up security +must be handed over to Oozie. + +The details of configuring Oozie for secure clusters and obtaining +credentials for a job can be found on the [Oozie web site](http://oozie.apache.org/) +in the "Authentication" section of the specific release's documentation. + +For Spark applications, the Oozie workflow must be set up for Oozie to request all tokens which +the application needs, including: + +- The YARN resource manager. +- The local HDFS filesystem. +- Any remote HDFS filesystems used as a source or destination of I/O. +- Hive —if used. +- HBase —if used. +- The YARN timeline server, if the application interacts with this. + +To avoid Spark attempting —and then failing— to obtain Hive, HBase and remote HDFS tokens, +the Spark configuration must be set to disable token collection for the services. + +The Spark configuration must include the lines: + +``` +spark.yarn.security.tokens.hive.enabled false +spark.yarn.security.tokens.hbase.enabled false +``` + +The configuration option `spark.yarn.access.namenodes` must be unset. + +## Troubleshooting Kerberos + +Debugging Hadoop/Kerberos problems can be "difficult". One useful technique is to +enable extra logging of Kerberos operations in Hadoop by setting the `HADOOP_JAAS_DEBUG` +environment variable. + +```bash +export HADOOP_JAAS_DEBUG=true +``` + +The JDK classes can be configured to enable extra logging of their Kerberos and +SPNEGO/REST authentication via the system properties `sun.security.krb5.debug` +and `sun.security.spnego.debug=true` + +``` +-Dsun.security.krb5.debug=true -Dsun.security.spnego.debug=true +``` + +All these options can be enabled in the Application Master: + +``` +spark.yarn.appMasterEnv.HADOOP_JAAS_DEBUG true +spark.yarn.am.extraJavaOptions -Dsun.security.krb5.debug=true -Dsun.security.spnego.debug=true +``` + +Finally, if the log level for `org.apache.spark.deploy.yarn.Client` is set to `DEBUG`, the log +will include a list of all tokens obtained, and their expiry details |